Electrode for arc lamps



(No Model.) I

I. L. ROBERTS.

ELECTRODE EOE ABG LAMPS.

No. 460,597. Patented Oct. 6, 1891.

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E g u p Wi'hasdas I I zwalztar I UNITED STATES PATENT OEETCE.

ISAIAH L. ROBERTS, OF BROOKLYN, NEW YORK.

ELECTRODE FOR ARC LAIVI PS.

.SPECIFICATION forming part of Letters Patent No. 460,597, dated October 6, 1891.

Application filed March 18, 1891. Serial No. 385,503- (No model.)

To all whom it may concern:

Be it known that I, ISAIAH L. ROBERTS, a citizen of the United States, and a resident of Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Pencils for Are Lamps, of which the following is a specification, reference being had to the drawing accompanying and forming a part of the same.

This invention is an improvement in electrio-arc lamps, and more particularly applies to the electrodes or pencils used in the same. Heretofore these pencils have usually been composed of carbon butit has also been proposed to make them of various materials, making, for example, both pencils of a refractory substance combined with carbon or metal or combining with a carbon positive pencil a metallic negative electrode.

According to my present invention I employ as one electrode for an arc lamp a pencil made up of a refractory substance which is a poor conductor associated with a conducting substance which may be either metal or carbon, and as the other electrode a pencil or its equivalent of carbon. I prefer to employ as the refractory material of the compound electrode a substance containing chromium or some of its compounds, and for the material of the other electrode I may employ any form of carbon pencil, such as is now used for are lamps.

One of the main objects now sought for in the improvement of electric-arc lamps is to obtain pencils which, other things being equal, shall burn more slowly than the carbon.

in present use. Composite carbons made up of a conductor associated with a highly-infusible substance may be made so as to consume very slowly; but whatis gained in this respect is lost in their greatly-increased electrical resistance. To utilize such pencils lamps have to be specially constructed for the purpose. I have found, however, that I may greatly increase the life of the pencils and utilize any of the existing arc lamps by combining with a composite pencil of the kind described a carbon pencil. Two electrodes of this kind will be consumed much more slowly than two of carbon or one of carbon and one of metal, and a much more satisfactory light will be produced.

The carbon electrode may be made up in any well-known way, provided it be composed essentially of carbon.

The compound pencil or electrode I prefer to make in any one of the following ways: I fill an iron or other metallic tube or holder with a substance containing chromiumsuch, for example, as chrome-iron ore in a finelydivided condition or chromous oxide or any metallic chromate or chromite-or I may associate the refractory substances named with a metal wire or a cylinder of wire-gauze or in other ways. Finally, I may mix together carbon and any of the substances named, both being finely powdered, and make of the mixture, by the use of a binding agent, pencils resembling the ordinary carbons, such pencils being molded and then baked, as in the process of making pencils of carbon in the usual manner.

Then carbon is used with the refractory material instead of metal, I prefer to use about sixty to eighty per cent. of carbon to from forty to twenty per cent., respectively, of such a substance as chromous oxide. When metal is used,the proportionate amount in the pencil will vary somewhat according to the nature of the material associated with it; but the best proportions are readily determined by experiment.

I have found that the positive pencil may be one of the compound pencils described and the negative an ordinary carbon pencil, or conversely; but that in either case the rate of the consumption is rendered slower, an exceptionally good light obtained, and a saving of expense effected.

I have shown in the accompanying drawing an arc lamp A of usual form, one pencil or electrode composed of a wire-gauze cylinder B, with a filling and coating of a refractory material C, which may be finely-powdered carbon and chrome-iron ore freed from earthy constituents. This composition is made into a mud with a solution of caustic soda or potash of about 10 Baum and worked into the tube or cylinder B. The other electrode D is a carbon rod or pencil.

What I claim is- 1. In an arc lamp, the combination of an electrode composed of aconducting substance and a refractory non-conducting substance,

substantially as described, and an electrode electrode composed of a metallic holder and of carbon, as set forth. a substance containing chromium and an IO 2. In an arc lamp, the combination of an electrode of carbon, as set forth. electrode composed of a conductor with which ISAIAH L ROBERTS 5 is associated a refractory substance containing chromium and an electrode of carbon, as Vitnesses: set forth. R0121. F. GAYLORD,

In an arc lamp, the combination of an PARKER XV. PAGE. 

